Al Qaeda Yemen Branch Plan Prompted U.S. Terror Alert

WASHINGTON—The terror plot that has temporarily shut down 19 U.S. diplomatic posts wasn't ordered by al Qaeda's leader Ayman al Zawahiri, but proposed by al Qaeda's Yemeni branch and approved by the global Qaeda chief, a senior U.S. official said Thursday in a more specific description of the plot's origin.

The intercepted communications of exchanges between Mr. Zawahiri and the leader of the Yemen branch, Nasser al-Wuhayshi, showed...